NSTAR ELECTRIC COMPANY AND SUBSIDIARY CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities:
Net Income	$ 1,228,046	$ 1,212,686	$ 916,572
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	1,103,008	981,380	885,278
Deferred Income Taxes	347,056	257,154	209,812
Pension, SERP and PBOP (Income)/Expense, Net	(14,693)	12,888	22,000
Pension and PBOP Contributions	(182,344)	(111,524)	(121,782)
Regulatory Underrecoveries, Net	(314,211)	(516,411)	(124,870)
Uncollectible Expense	60,886	53,461	63,446
Cost of Removal Expenditures	(242,130)	(148,332)	(153,477)
Other	(64,640)	(25,957)	(42,610)
Changes in Current Assets and Liabilities:
Accounts Receivables from Subsidiaries	(135,505)	(351,843)	(98,716)
Fuel, Materials, Supplies and REC Inventory	(1,859)	(15,404)	(8,074)
Taxes Receivable/Accrued, Net	(110,621)	43,819	(16,129)
Accounts Payable	(29,201)	122,567	14,866
Other Current Assets and Liabilities, Net	5,569	(9,591)	(11,603)
Net Cash Flows Provided by Operating Activities	1,962,600	1,682,572	2,009,577
Investing Activities:
Investments in Property, Plant and Equipment	(3,175,080)	(2,942,996)	(2,911,489)
Other Investing Activities	22,178	23,809	24,204
Net Cash Flows Used in Investing Activities	(3,447,374)	(4,129,275)	(3,274,288)
Financing Activities:
Cash Dividends on Common Shares	(805,439)	(744,665)	(663,239)
Cash Dividends on Preferred Stock	(7,519)	(7,519)	(7,519)
(Decrease)/Increase in Notes Payable	256,125	13,955	325,370
Issuance of Long-Term Debt	3,230,000	2,760,000	1,520,000
Retirement of Long-Term Debt	(1,142,500)	(327,236)	(801,078)
Other Financing Activities	(46,625)	14,273	(1,006)
Net Cash Flows Provided by Financing Activities	1,440,832	2,594,590	1,172,450
Net (Decrease)/Increase in Cash and Restricted Cash	(43,942)	147,887	(92,261)
Cash and Restricted Cash - Beginning of Year	264,950	117,063	209,324
Cash and Restricted Cash - End of Year	221,008	264,950	117,063
NSTAR Electric Company
Operating Activities:
Net Income	476,569	445,001	431,956
Adjustments to Reconcile Net Income to Net Cash Flows Provided by Operating Activities:
Depreciation	337,451	319,468	296,500
Deferred Income Taxes	57,507	72,595	27,107
Pension, SERP and PBOP (Income)/Expense, Net	(26,120)	(18,132)	(12,399)
Pension and PBOP Contributions	(30,000)	(650)	(6,359)
Regulatory Underrecoveries, Net	(79,075)	(186,081)	(60,863)
Amortization of Regulatory Assets, Net	55,774	83,248	103,735
Uncollectible Expense	16,649	15,293	25,079
Cost of Removal Expenditures	(58,967)	(39,166)	(44,363)
Other	(32,447)	(22,888)	(33,857)
Changes in Current Assets and Liabilities:
Accounts Receivables from Subsidiaries	(45,774)	(81,571)	(11,087)
Fuel, Materials, Supplies and REC Inventory	17,182	(9,834)	(9,858)
Taxes Receivable/Accrued, Net	(16,219)	(44,045)	14,147
Accounts Payable	31,650	25,573	(22,659)
Other Current Assets and Liabilities, Net	(3,238)	(32,997)	1,194
Net Cash Flows Provided by Operating Activities	700,942	525,814	698,273
Investing Activities:
Investments in Property, Plant and Equipment	(960,949)	(907,000)	(861,391)
Other Investing Activities	91	159	86
Net Cash Flows Used in Investing Activities	(960,858)	(906,841)	(861,305)
Financing Activities:
Cash Dividends on Common Shares	(283,200)	(262,000)	(181,800)
Cash Dividends on Preferred Stock	(1,960)	(1,960)	(1,960)
(Decrease)/Increase in Notes Payable		184,500
(Decrease)/Increase in Notes Payable	(32,500)		(268,000)
(Decrease)/Increase in Notes Payable to Eversource Parent	(21,300)	(9,000)	30,300
Capital Contributions from Eversource Parent	260,000	180,500	180,000
Issuance of Long-Term Debt	600,000	400,000	400,000
Retirement of Long-Term Debt	(250,000)	(95,000)	0
Other Financing Activities	(10,355)	(4,915)	(3,855)
Net Cash Flows Provided by Financing Activities	260,685	392,125	154,685
Net (Decrease)/Increase in Cash and Restricted Cash	769	11,098	(8,347)
Cash and Restricted Cash - Beginning of Year	17,410	6,312	14,659
Cash and Restricted Cash - End of Year	$ 18,179	$ 17,410	$ 6,312